RabbitMQ subscribe - rabbitmq

Question

I use RabbitMQ for connection between parts my program. Version of RMQ(3.3.5). It used with java client from repo.
// Connection part
#Inject
public AMQService(RabbitMQConfig mqConfig) throws IOException {
this.mqConfig = mqConfig;
connectionFactory.setHost(mqConfig.getRABBIT_HOST());
connectionFactory.setUsername(mqConfig.getRABBIT_USERNAME());
connectionFactory.setPassword(mqConfig.getRABBIT_PASSWORD());
connectionFactory.setAutomaticRecoveryEnabled(true);
connectionFactory.setPort(mqConfig.getRABBIT_PORT());
connectionFactory.setVirtualHost(mqConfig.getRABBIT_VHOST());
Connection connection = connectionFactory.newConnection();
channel = connection.createChannel();
channel.basicQos(1);
}
//Consume part
private static void consumeResultQueue() {
final QueueingConsumer consumer = new QueueingConsumer(channel);
Future resultQueue = EXECUTOR_SERVICE.submit((Callable<Object>) () -> {
channel.basicConsume("resultQueue", true, consumer);
while (true) {
try {
QueueingConsumer.Delivery delivery = consumer.nextDelivery();
String message = new String(delivery.getBody(), "UTF-8");
resultListener.onMessage(message);
} catch (IOException | InterruptedException e) {
e.printStackTrace();
}
}
});
}
I want leave use inifinty loop. Can RMQ notify client while message can read from queue? Without check?

Answer 1

You can create a class which extends DefaultConsumer and override handleDelivery.
public class MyConsumer extends DefaultConsumer {
public MyConsumer(Channel channel) {
super(channel);
}
#Override
public void handleDelivery(String consumerTag, Envelope envelope,
AMQP.BasicProperties properties, byte[] body) throws IOException {
// do your computation
}
}
And register this consumer with channel.basicConsume(queueName, myConsumerInstance);
Note that by doing this, handleDelivery will run inside rabbitmq client thread pool so you should avoid any long computation inside this function.